Prior art injection molding assemblies, for the manufacture of thin-walled containers, or similar items have previously been restricted in the size of container that can possibly be created, while maintaining the desired thin wall. Hot runner nozzles are typically positioned at a top end of the mold and melt is injected throughout the mold from this top end. This poses a difficulty with larger containers where extremely high pressure are required to inject melt to portions of the mold furthest away from the hot runner nozzles. While one solution is to provide for a thicker wall, this is not always feasible. In order to expand beyond this restriction, additional hot runner nozzles may be used, for example, positioned at side portions of the mold.
As known by those skilled in the art, where ribs or other features are to be provided on an external surface of the container, the mold includes side slide elements that provide for the external features on the container. In order to eject the container without causing damage to the external features of the container, the slide elements of the mold must move away, as a core half of the mold pulls away. Providing additional hot runner nozzles in the side portions, as discussed earlier, presents significant problems when portions of the mold are themselves moving.
Various prior art documents have attempted to address the problem of transferring melt into moving mold sections, including the slide elements discussed above, or alternatively, into tandem or stackable molds. Often times, these resulted in overly complex arrangements or requiring valves between interfaces that are prone to leakage. In other cases, the flow of melt has to be stopped when mold portions are in motion. Various other problems associated with the prior art will be evident to those skilled in the art. Various prior art patents and applications have attempted to address the problem of transferring melt into movable mold sections including Patent/Publication Numbers: U.S. Pat. No. 5,069,615 entitled “Stack Mold with Insulated Runner” published Dec. 3, 1991; U.S. Pat. No. 6,851,946 entitled “Hot Runner Distributor System” published Feb. 8, 2005; U.S. Pat. No. 7,614,869 entitled “Manifold Nozzle Connection” published Nov. 10, 2009; U.S. 2007/0193713 entitled “Transfer Of Force From Manifold To Plate Of Hot Runner” published Aug. 23, 2007; U.S. Pat. No. 7,284,979 entitled “Self Aligning Articulated Joint For Use In Hot Runner Systems” published Oct. 23, 2007; U.S. Pat. No. 5,484,275 entitled “Nozzle Construction For Triple Stack Molding Arrangement” published Jan. 16, 1996; U.S. Pat. No. 5,522,720 entitled “Injector Nozzle With Pivotally Movable Surfaces” published Jun. 4, 1996; U.S. Pat. No. 4,702,689 entitled “Side Mounted Manifold Block For Variable Orientation Of Injection Nozzle” published Oct. 27, 1987; Re. 35,256 entitled “Tandem Injection Molding Machine With Direct Feed To Molds” published May 28, 1996; U.S. Pat. No. 5,910,327 entitled “Sprue Bar Assembly For Stack Molds” filed Jun. 8, 1999; U.S. Pat. No. 5,804,231 entitled “Expandable Hot Runner Manifold” published Sep. 8, 1998; U.S. 2008/0193585 entitled “Hot Runner Interface Adaptor” published Aug. 14, 2008; U.S. Pat. No. 4,212,626 entitled “Stack Injection Molding Melt Transfer System” published Jul. 15, 1980; U.S. Pat. No. 7,775,788 entitled “Melt Transfer Components For A Stack Molding System” published Aug. 17, 2010; U.S. Pat. No. 6,955,534 entitled “Valve To Valve Melt Transfer Device” published Oct. 18, 2005; and, U.S. Pat. No. 5,011,646 entitled “Method And Apparatus For Injection Molding Using A Movable Sprue Bar” published Apr. 30, 1991.
Furthermore, the Variofill™ system sold by PSG Plastic Service GmbH discloses a system that permits variable positioning and movement of a hot runner assembly prior to functionally attaching same to a mold. However, once the hot runner is assembled into the mold, the movement of the hot runner assembly is fully constrained, and thus suffers from similar deficiencies as discussed above.
Accordingly, there is a need in the art for a hot runner manifold assembly that mitigates at least one of the aforementioned problems associated with the prior art and/or provides for improved performance in applications where there is a need for uninterrupted flow of melt between manifold portions that move with respect to each other.